Disclosed are a reporting method, a detection method, device and system for a network state. The reporting method for a network state includes: an intermediate node receiving a data packet; the intermediate node marking the data packet according to the current network state; and the intermediate node forwarding the marked data packet. The detection method for a network state includes: an aggregation node receiving a data packet; the aggregation node parsing the data packet to obtain the marking information about a network state; and the aggregation node determining the network state according to the marking information. The present invention solves the problem of heavy network burden due to the method of determining the network state by way of active inquiry, thus prolonging the service life of each node, and optimizing the performance of the system.